The misalignment of parts in thermomechanical and electromechanical transducers having one or more sprung, oscillating bodies causes these bodies to reciprocate along an axis other than the axis of geometric symmetry. The actual axis of reciprocation may be parallel but is generally not parallel to the geometric axis. Such misalignments arise routinely in the manufacturing and assembly of mechanical parts, because dimensions, angularity, and planarity cannot be made perfectly. In practice, machine designers define tolerances (i.e., tolerable deviations from perfection) on dimensions, angularity, and planarity, and when these imperfect parts are assembled, misalignments result.
Such misalignments may completely eliminate the physical clearance between a reciprocating body and its cylinder. The resulting mechanical contact causes friction, wear, and, in extreme cases, the seizing of the reciprocating body in its cylinder. Such mechanical contact may be lubricated by contact bearings, but the associated frictional energy dissipation degrades the efficiency of the transducer and the associated mechanical wear reduces its required maintenance interval or service life.
In electromagnetic electromechanical transducers ( such as those described in U.S. Pat. Nos 4,346 318 4,349,757, 4,454,426, 4,602,174, and 4,623,808), misalignment of the reciprocating body of the transducer introduces a radial magnetic force which increases the misalignment and thereby the force until the reciprocating and stationary parts are pulled tightly into unwanted mechanical contact.
In thermomechanical transducers (such as those described in U.S. Pat. Nos. 3,937,600, 3,947,155, 4,036,018, 4,179,630, 4,353,220, 4,538,964, 4,545,738, 4,644,851, 4,649,283, 4,721,440, 4,836,757, and 4,862,695) having a clearance seal between the reciprocating body and its cylinder, any eccentricity due to misalignments reduces the resistance to fluid flow through the clearance seal. If the reciprocating body is a piston, the increased flow of fluid through the clearance seal reduces the compression ratio achieved by the piston. If the reciprocating body is a displacer that pushes fluid through a system of heat exchangers, the increased flow of fluid through the clearance seal reduces the effectiveness of the intended heat transfer process.
Gas bearings (such as those described by J. W. Powell in Design of Aerostatic Bearings and elsewhere, and in U.S. Pat. No. 2,907,304, 3,127,955, 4,545,738, and 4,644,851) are desirable in thermomechanical and electromechanical transducers having one or more sprung oscillating bodies and in which energy efficiency and long service life are important, because they eliminate mechanical contact, friction and wear between the running surfaces of reciprocating bodies and their cylinders. Practical gas bearings cannot generate large radial forces for restoring a misaligned reciprocating body's axis of reciprocation acceptably close to the axis of geometric symmetry in such transducers, however, without dissipating an excessive amount of power, thereby degrading the energy efficiency of the transducer. The present invention reduces the amount of radial force that gas bearings must exert, and therefore the amount of power that they must dissipate, during operation to restore a misaligned reciprocating body's axis of reciprocation acceptably close to the axis of geometric symmetry in such transducers.